import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Main {
    public List<Integer> findSubstring(String s, String[] words) {
        List<Integer> ret = new ArrayList<Integer>();

        Map<String,Integer> hash1 = new HashMap<String,Integer>();
        for (String str : words) {
            hash1.put(str,hash1.getOrDefault(str,0) + 1);
        }

        int len = words[0].length();
        int m = words.length;
        for (int i = 0; i < len ; i++) { //执行次数
            Map<String,Integer> hash2 = new HashMap<String, Integer>(); // 保存窗口内所有单词的频次
            for (int left = i, right = i,count = 0; right+len <= s.length(); right+=len) {
                //进窗口 + 维护 count
                String in = s.substring(right,right+len);
                hash2.put(in,hash2.getOrDefault(in,0) + 1);
                if (hash2.get(in) <= hash1.getOrDefault(in,0)){
                    count++;
                }
                //判断
                if (right - left + 1 > len * m){
                    //出窗口+维护count
                    String out = s.substring(left,left+len);
                    if (hash2.get(out) <= hash1.getOrDefault(out,0)){
                        count--;
                    }
                    hash2.put(out,hash2.get(out) - 1);
                    left += len;
                }
                //更新结果
                if (count == m){
                    ret.add(left);
                }
            }
        }
        return ret;
    }
}






























